Thursday, September 23, 2010

I'm just taking a quick break from packing boxes and trawling through hepatic insulin resistance related to metabolic syndrome because I got (as always) side tracked. By hepatic glycogen storage this time, rather than lipid storage.

You have to giggle about glycogen storage disease type Ia. It may not be much fun if you have it, but at least you are protected against premature cardiovascular disease.

Of course, with lipids like those, you should die of CVD at a very early age. But you don't.

As people may recall my current hypothesis for the cause of premature CVD is that it is triggered by Purple Spotted sdLDL, something which is NEVER measured by lipidologists. This is hardly surprising because I made it up. Taking a lesson from the lipid hypothesis founders there.

So folks with glycogen storage disease type Ia have the worst possible lipid profile you can imagine and no premature CVD.

Guess what. People with glycogen storage disease type Ia are virtually never hyperglycaemic or hyperinsulinaemic. In fact hypoglycaemia can be a serious problem for them. But they don't get heart disease. Funny that.

Oh, and they are told to avoid fructose too (haven't checked why, but it seems like a good idea)... Perhaps I'm wrong about Purple Spotted sdLDL, it could just be that it's made of fructose rather than sucrose!

Saturday, September 18, 2010

An addendum to the mouse trans fat fibrosis paper: It's junk. Utter junk. Even the title is wrong. There are NO trans fats in the experiment, NONE what so ever!

The mice were fed on the Surwit Diet. Here's the pdf from Research Diets.

I thought medium chain trans fats were a bit of a strange animal....

So the mice are being fed on fully hydrogenated coconut oil, which has minimal PUFA to begin with and gets hydrogenated to fully saturated, mostly medium chain triglycerides. Plus non hydrogenated soya oil, which is mostly omega 6 PUFA and a little omega 3 PUFA.

The ONLY source of carbohydrate in the diet was sucrose and maltodextrin, which made up 25% of calories. To which they added sucrose in the drinking water, plus added fructose in the drinking water.

THERE ARE NO TRANS FATS IN THIS DIET.

Fructose, beyond human comprehension, with adequate soya oil, is enough to fibrose a mouse's liver. Not even Bill Clinton could eat this much fructose a day for life.

Who scrutineered this paper? Who wrote the title? How much money was wasted? What is happening in the world?

Thursday, September 16, 2010

I generally ignored this paper in 2008 as it didn't look particularly interesting and seemed mostly about fast food bashing, where the fast food included a large amount of sugar and starch. A bit like a real life Supersize Me, but with genuine average food intakes provided and individual responses in ALT levels, a marker traditionally associated with liver damage, also provided.

If anyone wants to eat 285g of sugar a day then they deserve whatever they have coming to them. What they have coming is an ALT increase which correlates with either carbohydrate or sugar intake by three weeks in to the feast. Not with fat.

I found the lack of association with fat disappointing. Sweden is a country fairly replete with trans fat and a little arithmetic applied to Table 1 (LeenaS describes these as "hidden fats") suggests that trans fat intake went from about 6g/d to 24g/d during the over feeding period of the study. This is not quite at the level of Crisco poisoning but I was still disappointed to see no discernible association with ALT. Ah well, you can't have everything.

Now I remember Tom Naughton nuking himself with trans fats during Fathead to the point of lowering his HDL, but otherwise he developed no suggestion of metabolic syndrome. But then Tom engaged his brain before drinking bucket loads of fructose and desisted from such stupidity. The fructose trick is for anyone with more Spurlockian intelligence.

To go back to Sweden: Gross overfeeding with "fast food" elevates your ALT. This is sort of boring because no one in their right mind is going to eat that much fructose in a month, which sort of defines Spurlock.

But was anyone still awake by the end of Supersize Me? Remember how long it took him to lose weight on his girlfriend's vegan cooking?

Now the question is, does this translate across in to the Swedish ovefeeding group? Well that was answered by a follow on study looking at the participants two and a half years down the road.

They're still fat. On average.

Something breaks in a month of overfeeding with trans fats and sugar. That is fascinating. Now you could argue that the volunteers got the taste for junk food, that their fat cells got stretched, that they were already self selected for being comfortable with gaining weight to take part in the study etc. I'd like to look a little more closely at liver pathology.

Elevated ALT is traditionally assumed to indicate liver damage. But there might be circumstances where you make more ALT in each cell, especially if a lot of amino acid processing is going on, so get benign ALT elevation. No one had a liver biopsy so it was impossible to find out exactly why the ALT went up.

Now, from a pathologist's point of view, a fatty liver is completely reversible. There is nothing permanently damaged in each hepatocyte or in the structure of the liver. Hepatic inflammation is also theoretically reversible. Those old leucocytes can leg it out just as easily as they legged it in.

But fibrosis, that's a different matter. Fibrosis is there to stay. This is at the micro architectural level. We're not talking cirrhosis (yet). No pathologist expects a fibrosed liver to go back to normal. It may adapt, regenerate, keep you alive, yes. But it's not normal. It will never be normal.

I picked up a link to a mouse study in which they fed chow, Super Crisco (medium chain trans fats, what are they?) or Super Crisco plus fructose enriched sucrose via the drinking water. The rest of the diet is not in the abstract so who knows what else they did. But it was the Super Crisco plus fructose/sucrose in the drinking water which made all of the headlines.

Super Crisco appears to be bad for your waistline but may not, on its own, produce the irreversible changes in the liver seen in the mice who combined it with HFCS. As far as you can tell from the abstract.

A diet replete in trans fats and HFCS fibroses your liver.

Translating from the Swedish volunteers and these poisoned mice to our two film directors:

Tom Naughton should be fine with his low fructose high trans fat diet and Spurlock should have aged his liver by a few years (in terns of insulin sensitivity) during his month of self poisoning on trans fats because he combined them with fructose to push his ALT through the roof.

I'll try and put this in to a physiology context when a little more time comes my way.

Peter

BTW: A methodological note from the initial Swedish study which adds the "human element" to the mind set of the "scientists" running it:

"If the subject was not able or willing to ingest the hamburger-based diet at any stage, it was changed to whatever food the participant accepted with the highest priority to achieve the calculated caloric intake and also, if the study subject still found it acceptable, a diet rich in protein and saturated animal fat."

My emphasis.

As always, it's nice when people nail their colours to the mast.

I see from Table 1 in the follow-on study that one man and one woman had actually reduced their weight to below their pre study weight by 2.5 years. I just wonder whether they were the ones who refused the trans fats of the hamburger diet and went with animal fat and protein to source their excess calories. No one is saying.

That human element gets everywhere!

EDIT: See Patrick's notes in the comments about the group leader from the hyperalimentation studies. A different impression from the published papers. There is hope for Sweden. Good.

Tuesday, September 14, 2010

From Randi, J. 1988. "The detection of fraud and fakery." Cell Mol Life Sci 44:287-288:

"Scientists are very easily deceived. They think logically, extrapolate possibilities from evidence presented, assume (with a good probability of being right) certain aspects of the observed data and draw upon their past experience in coming to decisions. This is to say that they act very much as all humans do, struggling with sensory input to derive new facts from it. But scientists do this with a certain authority and certainty born of their training and discipline. They are thus excellent candidates for being flimflammed by a clever operator who is aware of the fact that scientists seldom bring the human element into account."

Axen and Axen do not do either fraud or fakery. Their data are real. But the human element is essential.

Wednesday, September 01, 2010

OK, the biggest mistakes in A&A's 2006 paper was, in my book, Atkins bashing. There, I am biased. Citing the Atkins Diet specifically and using this citation as the basis for their study design is problematic. I don't know if A&A ever read ref 1 as cited but, believe me, these rats were not on the Atkins Induction or the subsequent Ongoing Weight Loss phases. Generally the Atkins diet involves Food plus artificial sweeteners and some easily avoidable non-foods such as soy flour. And vegetables.

So what did they do? They took a group of lab rats and made them obese with trans fatty acid enriched Crisco as 60% of their calories. They then split the rats in to two groups, one was given 60% of calories as carbohydrate through out. The other group was given 5% carbohydrate for 2 weeks then 15% carbohydrate for a month, à la Atkins. Both groups were moderately energy restricted, dictated by a somewhat random decision protocol.

There was a parallel group eating crapinabag (CIAB) throughout (no Crisco). Glucose tolerance tests, with insulin measured at 20 minutes, were performed at various time points.

What went wrong in 2006?

Things started well with the Crisco rats having higher blood glucose at 10 minutes in to the GTT than the CIAB rats. Insulin levels were a lot higher in the Criso rats 20 minutes in to the test by which time glucose was identical between Crisco and CIAB groups. That's Graph A. Crisco causes insulin resistance.

Things were going reasonably well for Atkins bashing at the end of the two week "Atkins Induction" phase. During GTT the 60% carb group were slightly lower in glucose and this made p<0.05 at 10 minutes. However the cracks are beginning to show. The "Atkins Induction" group had an insulin at 20 minutes in to GTT of 600pM, the 60% carb group needed an insulin of over 900pM to achieve the marginally lower glucose level at this point. The insulin values were, luckily for A&A, not significantly different. Fasting insulin at this point was also lower in the "Atkins Induction" group. A&A were lucky on the p values here too. Here's graph B with that spiked glucose at 10 minutes:

By the end of the experiment at 14 weeks the Atkins Group had been given more (15% of calories) carbohydrate. The GTT at this time point is shown here:

Now you need to get your glasses on for this one. Can you see any difference between the "Atkins Ongoing Weight Loss" (VLC) group and the 60% carbohydrate (HC) weight loss groups? No? Me neither.

Insulin values were slightly better in the 60% carb group but again nothing significant. Both weight loss groups had lower insulin values than the CIAB group! All NS again.

So there we have it: Atkins Ongoing Weight Loss, as interpreted by A&A, gives a GTT curve which is superimposed on the 60% carbohydrate weight loss group. ATKINS is GOOD!

There is a load of bollocks in the discussion about the impaired insulin response in the Atkins group in graph B. To me shifting glucose with a lower insulin level is good, not bad. The spike at 10 minutes is the only saving grace to the funding generating ability of this study.

But graph C is just hysterical.

Okay, A&A are not stupid. They worked out exactly what went wrong in graph C and what was going well in graph B.

So they went out and got more funding to demonstrate CONCLUSIVELY that the Atkins Diet makes you diabetic. They got that funding. These people are good, make no mistake. They got the desired result second time round. How many people get a second chance like this? They published in 2010.

Here is graph a from 2010, directly comparable to graph A from 2006.

Very similar but tidied up in 4 years of refining the model. Or maybe the CIAB has been improved. Anyhoo, same result. Crisco does nasty things to GTT curves.

Next is graph b, which is like graph B above but is after a month rather than 2 weeks and has the on going Crisco group included. The very low carbohydrate group is looking a lot like the Crisco group by now...

But here is the Money Shot in graph c from 2010. Just look at the Crisco curve (HF) and the 5% carbohydrate (VLC) curve. Just look at that fit!

I told you these people were good!

But also go back and look at the blooper graph C from 2006.

So what is going on?

There is a nice pointer in line seven of Table 2, "Soleus TAG". This is the amount of intra myocyte lipid in a typical muscle. It is a marker of how reluctant that muscle is going to be to accept glucose. Two groups have high soleus TAG. The Crisco poisoned (HF) group throughout and the VLC group at 16 weeks.

The explanations for why these two groups have high soleus TAG is likely to be different. Both will, in all certainty, reflect elevated FFAs in the plasma. But the Crisco poisoned group will have elevated FFAs, 24/7, despite 15% of calories as starch. We know from the 2006 blooper that 15% of calories as starch will give a GTT curve in VLC rats which matches the 60% carb group EXACTLY. Not so if you are Crisco poisoned.

The VLC rats on 5% of carbs will have elevated FFAs 24/7 because they would be dead without them. They are on a starvation diet of which only 5% is carbs. Without FFAs they would run their muscles on glucose. They don't get enough glucose per day to do this and still keep their brain alive. Death is not an option.

So the Crisco group has elevated TAG in soleus muscle in the presence of carbohydrate in the diet. It's pathological. The VLC group has elevated TAG in their soleus muscle because they had minimal free glucose available, which is physiological.

BTW either fasting or a brief period without carbohydrate will promptly elevate muscle TAG in humans. It is an utterly normal response to a reduced supply of glucose. The actual signal for muscle insulin resistance is not likley to be the tri acyl glycerol molecules themselves because athletes have bucket loads of this without insulin resistance. More likely is a more ephermeral moiety such as Acyl-CoA molecules or diglycerides which more closely reflect FFA supply. In a GTT the glucose supply is massively supraphysiological. For insulin sensitivity to return to LC muscles it takes time for insulin to spike, insulin to get to adipocytes, adipocytes to respond to insulin, FFA level in blood to drop and FFA derivative level in muscle to drop. It's hardly surprising that the 10 minute glucose peak was higher in the VLC rats during GTT. However, as soon as the muscles clear FFA derivatives they are still geared up to go with glucose, nae problem, nae bother. I'll come on to issues with insulin later. Obviously the Crisco poisoned rats are obese and their adipocytes will have an inability to suppress FFA release in response to insulin. That's how it is if you eat Crisco.

Let's look at the insulin responses. All of the fasting insulin levels were about the same. Obviously the VLC had the lowest insulin and almost certainly the lowest HOMA score although p might still have been > 0.05. By week 16 the insulin response to GTT was interesting.

The VLC rats mimicked the Crisco (HF) group's glucose curve. But they did it with just 1.79ng/ml of insulin. The Crisco rats needed 2.93ng/ml of insulin (p<0.05). The lower curve with open diamonds is the 60% carb group. The curve looks good until you realise that these rats needed as much insulin as the Crisco rats to achieve this beautiful curve, nearly twice that in the VLC group (2.95ng/ml vs 1.79ng/ml, p<0.05).

So which rats are the most insulin sensitive? Not the Crisco rats. I'll accept that. Just say no to Crisco... It is completely arguable between the VCL and 60% carb group.

BUT. What would have happened if the VLC group had produced the same insulin response as the 60% carb group? Impossible, scream Axen and Axen. The VCL group have a blunted insulin response. It makes them well on the road to diabetes, metabolic syndrome, blindness, dialysis, we need the funding...

I have to thank Helen who placed a comment on another post. She pointed out that glucokinase in the pancreas, the enzyme which the pancreas uses to sense glucose in the portal blood, is down regulated in response to carbohydrate restriction. Oh.

It is, err, up regulated in carbohydrate surplus.

This is what "bit" Axen and Axen in 2006. It looks like 15% of calories as carbohydrate in a VLC non-Crisco situation is adequate (on a high protein background) to allow pancreatic insulin secretion in response to glucose to become identical to that produced by rats on a 60% carbohydrate diet. Muscle TAG and associated molecules will drop too. Hence the overlay of the GTT curves in 2006.

Let us assume, very reasonably, that the VLC rats in 2010, on a 5% carb, energy restricted diet, are not expecting to deal with hyperglycaemia any time soon. They down regulate glucokinase production. Then some joker injects 1g/kg of glucose in to their peritoneal cavity. No one up regulates their glucokinase in 10 minutes, not even Super Rat*. Insulin response is blunted. Hyperglycaemia results.

*Actually Super Rat could do this but she is always busy saving the planet (again) and doesn't have time to help out here.

What would have happened with a few days carb loading in the VLC group before the GTT? Well, we (that "we" includes A&A) know the answer to this from 2006. Did you really think A&A are stupid? How many times do I have to point out that these people are good. Very, very good. They know that to get a "bad" result for VLC you must NOT increase carbs pre glucose load in a GTT.

Does anyone think that neither Axen nor Axen has heard of glucokinase? That would mean they're stupid. They're not, they know that if they allowed 15% carbs for a few days the VLC group would overlay the curve of the 60% carb group. For crying out loud, they published the damned curves themselves!

No. The effect of increased carbs on a VLC is not "unclear" (their word). It adjusts pancreatic insulin secretion to deal with carbs when carbs form a significant part of the diet. That's called physiology!

In summary:

Do A&A have a paradigm to support, a mortgage or two to pay, a living to make, careers to develop?

A few fatties getting injured is of no concern, provided the models can be adjusted to keep the funding coming through.

Will people edging towards type 2 diabetes get injured by a very low carbohydrate diet or will they be injured by A&A's funding success? What if they eat low fat high carbohydrate in the real world? What is hunger?

About Me

I am Petro Dobromylskyj, always known as Peter. I'm a vet, trained at the RVC, London University. I was fortunate enough to intercalate a BSc degree in physiology in to my veterinary degree. I was even more fortunate to study under Patrick Wall at UCH, who set me on course to become a veterinary anaesthetist, mostly working on acute pain control. That led to the Certificate then Diploma in Veterinary Anaesthesia and enough publications to allow me to enter the European College of Veterinary Anaesthesia and Analgesia as a de facto founding member. Anaesthesia teaches you a lot. Basic science is combined with the occasional need to act rapidly. Wrong decisions can reward you with catastrophe in seconds. Thinking is mandatory.
I stumbled on to nutrition completely by accident. Once you have been taught to think, it's hard to stop. I think about lots of things. These are some of them.

Organisation (or lack of it)!

The "labels" function on this blog has been used to function as an index and I've tended to group similar subjects together by using labels starting with identical text. If they're numbered within a similar label, start with (1). The archive is predominantly to show the posts I've put up in the last month, if people want to keep track of recent goings on. I might change it to the previous week if I ever get to time to put up enough posts in a week to justify it. That seems to be the best I can do within the limits of this blogging software!